Wrong rowspan after vertically splitting and merging back cells

[nitesh]

Add a table using the default options:

<table border="1" cellpadding="1" cellspacing="1" style="width: 500px">
	<tbody>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
	</tbody>
</table>
<p>
	&nbsp;</p>

The split the first cell vertically:

<table border="1" cellpadding="1" cellspacing="1" style="width: 500px">
	<tbody>
		<tr>
			<td>
				&nbsp;</td>
			<td rowspan="2">
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
	</tbody>
</table>
<p>
	&nbsp;</p>

Then merge the first cell down:

<table border="1" cellpadding="1" cellspacing="1" style="width: 500px">
	<tbody>
		<tr>
			<td rowspan="2">
				&nbsp;</td>
			<td rowspan="2">
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
	</tbody>
</table>
<p>
	&nbsp;</p>

It should revert to the original layout, i.e. the first set of html pasted, but instead the first row ends up with four table cells, and the second row ends up with just two.